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Exam 2
Ch 5, 10-12
103
Biology
Undergraduate 3
03/19/2014

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Term
How is the number of mitochondria increased?
Definition
Through fission of preexisting mitochondria
Term
When fusion of mitochondria becomes more frequent than fission, the mitochondria tend to become __________.
Definition
more elongated and more interconnected
Term
What is the origin of the inner mitochondrial membrane?
Definition
the membrane of the ancestral bacterium that was phagocytosed
Term
Which of the following statements about the inner mitochondrial membrane is NOT true?
A. It is rich in cholesterol.
B. It has a very high protein/lipid ratio.
C. It is rich in cardiolipin.
D. It may have evolved from the bacterial plasma membrane
Definition
It is rich in cholesterol
Term
Which of the processes below leads to the formation of more numerous and distinct mitochondria in a cell?
Definition
fission from preexisting mitochondria
Term
The outer membrane of the mitochondrion appears to be derived from _______.
Definition
the outer membrane found in certain bacterial cell walls
Term
Which of the following is a component of the mitochondrial matrix?
A. DNA
B. enzymes
C. ribosomes
D. All of the above
Definition
all of these
Term
Which of the following statements about mitochondria is(are) NOT true?
A.They are found in plant cells.
B.They contain two membranes.
C.They are found in bacterial cells.
D.They are found in plant cells and contain two membranes
Definition
They are found in bacterial cells
Term
What advantage do the cristae confer on the mitochondria?
Definition
They greatly increase the surface area for aerobic respiration machinery
Term
Organisms that lack the ability to use molecular oxygen to extract more energy from their foodsuffs most likely excrete _______.
Definition
lactic acid.
Term
What is a gene?
Definition
a unit of inheritance
Term
What are alleles?
Definition
alternate forms of a gene for the same trait
Term
When both a dominant and recessive allele for a particular gene are present together in the same plant ______________.
Definition
the recessive allele is masked by the dominant allele and the dominant allele is always expressed
Term
The Law of Independent Assortment states that ____________.
Definition
segregation of an allelic pair for one trait has no effect on segregation of alleles for another trait
Term
The behavior of what cell constituent correlated perfectly with that of Mendel's genetic factors?
Definition
the homologous pairs of chromosomes
Term
What is a linkage group?
Definition
genes on the same chromosome following nonindependent assortment
Term
What causes the appearance of large chromosomes in the salivary glands of Drosophila larvae?
Definition
Duplicated DNA strands remain attached to each other in perfect side-by-side alignment
Term
In analyzing the number of different bases in a DNA sample, which result would be consistent with Chargaff’s findings?
Definition
A + G = C + T
Term
How do topoisomerases I and II differ from one another?
Definition
Type I makes a transient break in one strand while type II makes a transient break in both strands
Term
If the temperature of a solution containing DNA is raised, it will eventually reach a point at which the double helix separates into its two component strands. The process by which this occurs is called ______.
Definition
denaturation
Term
Which of the following is a factor that determines the rate of renaturation of a given DNA preparation?
A.ionic strength of the solution
B.size of the interacting molecules
C.period of incubation
D.all of these answers are correct
Definition
all of these answers are correct
Term
What type of DNA sequences range from about 10 to 100 base pairs and are found in clusters containing as many as 3,000 repeats? These sequences tend to be unstable with the number of copies of a particular sequence often increasing or decreasing from one generation to the next, as a result of unequal crossing over. They can alter expression of nearby genes, which, in turn, can have serious outcomes; they have been implicated as a cause of cancer and diabetes.
Definition
minisatellite DNAs
Term
What process is generally thought to produce gene duplication?
Definition
unequal crossing over
Term
Conserved portions of mammalian genomes are assumed to be _________.
Definition
important
Term
Alternative splicing accounts for the fact that ___________.
Definition
the actual number of proteins encoded by the human genome is at least several times greater than the number of genes it contains
Term
The most common type of genetic variability in humans occurs at sites in the genome where single nucleotide differences are found among different members of the population. What are these sites called?
A.single nucleotide polymorphisms
B.SNPs
C."snips"
D.all of these answers are correct
Definition
all of these answers are correct
Term
What is the major determinant of RNA folding?
Definition
formation of regions having complementary base pairs
Term
Why has the One Gene – One Polypeptide hypothesis had to be modified?
Definition
Genes can be spliced alternatively to generate a variety of related polypeptides
Term
The enzyme in eukaryotes that is responsible for the synthesis of RNA from a DNA template is called _______.
Definition
DNA-dependent RNA polymerase
Term
Proteins that help cellular RNA polymerases recognize promoters are called __________.
Definition
transcription factors
Term
Sequences of DNA that are similar, seemingly conserved and seen in association with genes in roughly the same location from gene to gene in bacteria are called ________. They are generally the most common version of such a conserved DNA sequence, but some variation in the sequence can occur from one gene to another.
Definition
consensus sequences
Term
Reactions leading to nucleic acid and protein synthesis are inherently different from those of intermediary metabolism. Such reactions must be essentially ________. The synthesis of polynucleotides is thus coupled to ________ _________ hydrolysis.
Definition
irreversible, exergonic, pyrophosphate
Term
You are looking at an electron micrograph of several transcriptional units for rRNA. How can you tell where the transcription initiation site is?
Definition
It is near the shortest nascent transcripts
Term
The macromolecular complex that associates with each intron and splices it is called a(n) _____.
Definition
spliceosome
Term
What is the average number of adenosine residues added to the end of an mRNA to build the poly(A) tail?
Definition
about 250
Term
Which of the following describes the normal range of half-lives for mRNAs?
Definition
about 15 minutes to a period of days
Term
An antisense RNA for a particular targeted protein is ___________.
Definition
an RNA having a sequence complementary to the mRNA of the targeted protein that is of interest
Term
RNA interference refers to ________.
Definition
double-stranded RNAs inducing the selective destruction of mRNAs having identical sequences
Term
The greatest variability among codons specifying the same amino acid occurs _________.
Definition
in the third nucleotide of the triplet
Term
A tRNA has an anticodon with the sequence 3'-GAC-5'. What would be the sequence of the complementary codon? For the moment do not consider the wobble hypothesis.
Definition
5'-CUG-3'
Term
From what does nonsense-mediated decay (NMD) protect the cell?
Definition
from producing non-functional, shortened proteins
Term
What would occur if the repressor of an inducible operon were mutated so that it could not bind the operator?
Definition
There would be continuous transcription of the operon’s genes
Term
Which of the following sequences represents decreasing levels of chromosomal organization from most condensed to most dispersed?
Definition
mitotic chromosomes – supercoiled loops – 30 nm filaments -- nucleosomes
Term
Which of the following histones is referred to as a linker histone?
Definition
H1
Term
What group of proteins associated with DNA could be described as a small, well-defined basic protein group that exhibits very high lysine and/or arginine content?
Definition
histones
Term
What cells typically retain telomerase activity and thus maintain their telomeres at a constant length?
Definition
germ cells
Term
You are studying two chromosomes, one (chromosome 10), which carries no genes that are active in the cells being studied, and the other (chromosome 13), which is rich in protein-coding sequences, most of which are transcribed in the cells you are studying. Where would these chromosomes be likely to be located within the interphase nucleus?
Definition
Chromosome 10 would be in the heterochromatin; chromosome 13 would be in the euchromatin
Term
When lactose is present in the bacterial culture medium, which of the following is true of the bacteria cultured therein?
A.Lactose (or allolactose) binds to the repressor, changing its shape and preventing its binding to the operator.
B.The structural genes of the lac operon are transcribed.
C.The lac operon enzymes are synthesized and lactose is catabolized.
D.All of these are correct answers.
Definition
All of these are correct answers
Term
What is the relationship between cAMP levels in bacteria and glucose concentration in the medium?
Definition
As glucose levels rise, cAMP levels drop
Term
In the trp operon, __________ in the absence of tryptophan.
A.the operator site is open to allow RNA polymerase binding
B.the trp operon structural genes are transcribed
C.the tryptophan-synthesizing enzymes of the trp operon are synthesized
D.all of these answers are correct
Definition
all of these answers are correct
Term
You are growing E. coli in culture in the presence of lactose and glucose. Which of the following events takes place?
Definition
Glucose is metabolized
Term
How are enhancers thought to stimulate transcription despite the large distance separating them from the core promoter?
Definition
Enhancers and core promoters can be brought into close proximity because the intervening DNA can form a loop and be held there through the interactions of DNA-bound proteins.
Term
You are working with adult mouse fibroblast cells. The genes for transcription factors from pluripotent stem cells are transduced into the adult fibroblast cells as part of viral vectors in various combinations and once inside the cells they were expressed, causing the cells to behave like ES cells. Which of the following is a true statement about this experiment?
A.The introduction of the genes for a combination of only four specific transcription factors was sufficient to reprogram fibroblasts into cells that behaved like pluripotent ES cells.
B.The introduced genes are silenced as the cells' endogenous genes governing pluripotency are activated.
C.The cellular reprogramming process occurs gradually as the cells divide in culture.
D.All of these answers are correct.
Definition
All of these answers are correct
Term
What domain of a transcription factor regulates transcription by interacting with other proteins?
Definition
activation domain
Term
You attempt deletion mapping of a part of the promoter region of a particular gene. You remove a short sequence of nucleotides. Once the altered DNA is transfected into cells, the cells are able to transcribe the transfected DNA in a normal fashion. What do you conclude?
Definition
The sequence that was removed is not an essential part of the promoter
Term
What effect can mRNA editing have on an mRNA?
A.It can create new splice sites.
B.It can generate stop codons.
C.It can lead to amino acid substitutions.
D.All of these answers are correct
Definition
All of these answers are correct.
Term
What may happen if a protein that is supposed to have a short survival time and that is involved in the initiation of cell division is not destroyed when it is supposed to be destroyed?
Definition
The cells may become malignant
Term
A section of a bacterial chromosome in which genes for the enzymes of a particular metabolic pathway are clustered together in a functional complex under coordinate control is called a(n) ______.
Definition
operon
Term
Why has the One Gene – One Polypeptide hypothesis had to be modified?
Definition
Genes can be spliced differently to generate a variety of related polypeptides.
Term
What domain of a transcription factor is responsible for recognizing and associating with specific DNA base pair sequences?
Definition
the DNA-binding domain
Term
Sequences of DNA that are similar, seemingly conserved and seen in association with genes in roughly the same location from gene to gene in bacteria are called ________. They are generally the most common version of such a conserved DNA sequence, but some variation in the sequence can occur from one gene to another.
Definition
consensus sequences
Term
The information encoded in DNA resides in ________.
Definition
the DNA base sequence
Term
What happens if histone H1 is selectively extracted from compacted chromatin (30 nm fibers)?
Definition
30-nm fibers uncoil to form a thinner, more extended beaded filament
Term
Why do your muscles hurt for some time after a large amount of anaerobic exercise?
Definition
During anaerobic exercise, you cannot take in enough oxygen to act as the final electron acceptor of the electron transport chain. As a result, you cannot regenerate NAD+ or FAD+ fast enough, and the Krebs cycle gets backed up. Your cells therefore shift to anaerobic lactic acid fermentation. Lactic acid is insoluble and precipitates as sharp crystals that cause pain.
Term
You are looking at an electron micrograph of several transcriptional units for rRNA. How can you tell where the transcription initiation site is?
Definition
It is near the shortest nascent transcripts
Term
How short must the poly(A) tail get to cause the mRNA to be degraded rapidly?
Definition
about 30 adenosine residues
Term
Scientists often stain chromosomes from mitotic cells and photograph the chromosomes in the microscope. Each chromosome is cut out of the photograph, the chromosomes are matched up in homologous pairs and they are placed in order of decreasing size. These pictures can be used to screen individuals for chromosomal abnormalities, like extra, missing or grossly altered chromosomes. What is such a picture called?
Definition
karyotype
Term
When both a dominant and recessive allele for a particular gene are present together in the same plant, _________.
1) the recessive allele is always expressed
2) the dominant allele is expressed some of the time
3) the dominant allele is always expressed
4) the dominant allele is masked by the recessive allele
Definition
3
Term
Transcription factors bound at the enhancer stimulate the initiation of transcription at the core promoter through the action of intermediaries called _____.
Definition
coactivators
Term
What is the terminal electron acceptor of the electron transport chain?
Definition
O2
Term
Electrochemical gradients have both a(n) _________ and a(n) __________ component
Definition
concentration, electrical
Term
Where are most of the enzymes of the Krebs cycle located?
Definition
in the soluble phase of the mitochondrial matrix
Term
Transcribe and translate the following fragment of the following gene:
3’ CATACGAAGACTTCCGAGATCTCGTAATTACCCT 5’
Definition
5’ GU AUG CUU CUG AAG GCU CUA GAG CAU UAA UGG GA 3’
Protein: Met-Leu-Leu-Lys-Ala-Leu-Glu-His-STOP
Term
When a gene has been duplicated one or more times, what are the possible things that can happen to the duplicated gene?
a. The duplicated gene can accumulate favorable mutations and acquire a new function.
b. The duplicated gene can be lost during evolution through deletion.
c. The duplicated gene can be rendered nonfunctional by unfavorable mutations.
d. If there are two copies of the gene, both could undergo mutation so that each evolves a more specialized function than the original gene.
e. All of these are correct.
Definition
All of these are correct
Term
The success of cloning experiments led to the conclusion that _________.
1) the transcriptional state of a differentiated cell is not irreversible
2) the transcriptional state chromatin in a differentiated cell is irreversible
3) the transcriptional state chromatin in a differentiated cell is not irreversible
4) a nucleus from a differentiated cell can be reprogrammed by factors residing in the cytoplasm of its new environment
Definition
1, 3 and 4
Term
A single gene can encode a number of related proteins as a result of a process called _______.
Definition
alternative splicing
Term
Why are general transcription factors (GTFs) referred to as "general?"
Definition
The same transcription factors are required for the accurate initiation of transcription of a diverse array of genes in a wide variety of different organisms
Term
What advantage do the cristae confer on the mitochondria?
Definition
They greatly increase the surface area for aerobic respiration machinery.
Term
________ plays a key role in replicating DNA at the ends of chromosomes.
Definition
Telomerase
Term
Describe the structure and function of the trp operon.
Definition
The tryptophan operon (trp operon) is a cluster of 5 genes in bacteria that are involved in producing tryptophan. When cellular levels of tryptophan are high, extra trp binds to a repressor protein, which then associates with the operator region of the operon. This blocks transcription. As trp levels fall, the repressor protein no longer has trp and it dissociates from the operon, which allows polymerase to bind to the promoter of the operon and transcribe the genes, so the cell can produce more trp.
Term
What chemical group is attached to the first methionine in a polypeptide chain in prokaryotes?
Definition
a formyl group
Term
The direct formation of ATP by the transfer of a phosphate group from a donor molecule to ADP is called ________.
Definition
substrate-level phosphorylation
Term
When present, the TATA, CAAT and GC boxes are typically found within 100 – 150 bp upstream from the transcription start site. Due to their closeness to the start of gene, they are often called ______.
Definition
proximal promoter elements
Term
Covalent linkage to what small, highly-conserved protein marks proteins for destruction?
Definition
ubiquitin
Term
What does it mean if portions of the noncoding regions of the genome are conserved?
Definition
Introns and other supposedly useless, noncoding parts of the genome actually have important, unidentified functions.
Term
The operator __________.
Definition
is the site on the DNA where the repressor binds
Term
What extends from the methylguanosine cap at the start of an mRNA to the AUG initiation codon?
Definition
the 5' UTR
Term
What drives the rotation of the F1 head of ATP synthase?
Definition
proton movement from intermembrane space to the matrix
Term
What molecule is responsible for conveying 2 carbons from pyruvate to the Krebs cycle?
Definition
Coenzyme A
Term
The three catalytic sites of ATP synthase ___________.
a. have different substrate binding affinities
b. have different product binding affinities
c. at any one time are present in different conformations
d. pass sequentially through their three different conformations
e. All of these are correct.
Definition
All of these are correct
Term
What energy source other than ATP hydrolysis do mitochondria, unlike most other organelles, routinely use to power their activities?
Definition
proton-motive force
Term
The macromolecular complex that associates with each intron and splices it is called a(n) _____.
Definition
spliceosome
Term
The building blocks of a nucleotide are ___________.
Definition
a pentose sugar, a phosphate group and a nitrogenous base
Term
The 3' end of most eukaryotic mRNAs contains a ______, while the 5' end has a _________.
Definition
poly(A) tail, methylated guanosine cap
Term
You are working with adult mouse fibroblast cells. The genes for transcription factors from pluripotent stem cells are transduced into the adult fibroblast cells as part of viral vectors in various combinations, and once inside the cells they were expressed. Cells are produced that are capable of dividing indefinitely in culture and of differentiating into all of the various types of the body's cells. What are they called?
Definition
both iPS cells and induced pluripotent cells
Term
Another name for protein synthesis is _________.
Definition
translation
Term
Which of the following is an RNA nucleoside?
Definition
cytosine and ribose
Term
What statement below explains the uniform width of the DNA molecule along its entire width?
Definition
A pyrimidine nitrogenous base always pairs with a purine nitrogenous base
Term
The greatest variability among codons that specify the same amino acid occurs _________.
Definition
in the third nucleotide of the triplet
Term
While the tall allele for plant height is dominant over the short allele, the round allele for seeds is dominant over the wrinkled allele. If pure-breeding tall plants with wrinkled seeds are mated to pure-breeding short plants with round seeds, what is the genetic makeup of the F1 generation resulting from this cross? If the traits assort independently, what ratio of offspring would be expected in the F2 generation resulting from a cross of two F1 individuals?
Definition
The parents in this case are tall-wrinkled (TTrr) and short-round (ttRR). The F1 cross would be 100% heterozygous (TtRr). If the traits assort independently, then a 9:3:3:1 ratio is expected in the F2 generation of offspring. That’s basic Mendelian inheritance!
Term
In which of the following organisms is polyploidization particularly common?
a. flowering plants
b. wheat
c. bananas
d. coffee
e. All of these are correct.
Definition
All of these are correct
Term
Chapter 5: This chapter dealt with aerobic metabolism. There were 3 main stages to this: Krebs, electron transport, and ATP synthesis. Therefore, you should expect that the exam might include one of the following essay questions. You should be able to answer any or all of these.
•Describe the complete metabolism of pyruvate to CO2, including the names of all intermediate compounds and electron carriers.Specifically note where each carbon from pyruvate is lost as CO2.
•Describe the electron transport chain in the mitochondria.
•Describe how the ATP synthase enzyme works.
Definition
Chapter 10: This chapter mostly dealt with the structure of DNA and basic inheritance. It does not lend itself well to essay-format questions. Your practice test contains one question. Be aware that I may have multiple variants of this question (or similar questions).
Term
Chapter 11: This chapter dealt with transcription, splicing, and translation. You can anticipate that I WILL ask you transcribe and translate a gene sequence. Make sure you can do this correctly! I put tremendous emphasis on your ability to do this! There are many sites online with practice problems. I suggest starting with http://learn.genetics.utah.edu/content/molecules/transcribe/ and searching the internet for “Transcription Translation Practice” as a search phrase.
Definition
Chapter 12: This chapter was about gene regulation. You should be able to answer the following questions or types of questions:
• The madeup operon regulates a particular set of genes involved in creative thought. Describe what you would expect in terms of the operon structure and how it might be regulated when writing a non-creative paper (such as a research paper).
• Compare and contrast gene regulation in bacteria and eukaryotes.
• Describe the main levels at which gene expression may be controlled in eukaryotes and provide at least one example of a control mechanism per level.
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